The present invention relates to an apparatus and a method for producing signals responsive to the colour of each of a succession of objects being examined. The objects may for instance be edible products such as peas or sweets, but the invention is in no way limited to edible products. Colour can be any or all of: hue, saturation and lightness.
The measurement of colour of irregular or complex-shaped transparent or reflecting objects presents problems. The light scattered by such objects may be collected by an integrating sphere whilst the object is illuminated from a specific direction, but this has the disadvantage that the direction of illumination is arbitrary and different orientations of the object may lead to different results being obtained. Alternatively, the object may be illuminated diffusely whilst being viewed from one or a number of specific directions, again leading to the same disadvantage.